1. Field of the Invention
This invention generally relates to sodium cooled pool-type nuclear reactors and, more particularly, to an arrangement for thermally isolating the hot sodium used in these reactors from the structural components of the reactor.
2. Description of the Prior Art
Pool-type nuclear reactors are characterized by the placement of a reactor core, a main circulating pump and a main heat exchanger within a single primary system boundary which acts as a container. Typically these reactors are designed for use with liquid metal coolant and the primary system boundary or reactor vessel holds all of the components in a pool of sodium much like a large cup.
Generally, in pool-type reactors, the coolant is pumped from a cold plenum through and into the core and is thereafter discharged into a hot plenum. From the hot plenum the coolant flows through the main heat exchangers and transfers the heat energy picked up in the reactor core to a secondary coolant. The primary coolant is thereafter discharged back into the cold plenum. The secondary coolant is pumped out of the reactor vessel and is used for power generation.
In sodium cooled pool-type nuclear reactors there is a major design problem in isolating the pool of hot sodium from the load bearing, structural members of the reactor. Sodium cooled pool-type reactors are presently designed to operate with a hot plenum pool temperature in excess of 800.degree. F. and the design disclosed herein for a super-heated steam cycle operates with a hot pool temperature of 950.degree. F. These temperatures are all substantially above the nominal maximum design temperature of 800.degree. F. for stainless steel. Above this temperature stainless steel commences to creep and the reactor must be designed to thermally insulate the high temperature sodium from contacting the load bearing components of the reactor.
Over the years there have been many solutions to this problem including the use of an insulated internal tank for separating the hot coolant in the hot plenum from the reactor vessel wall. In one existing pool reactor design a plenum separator in the form of a cylindrical shell is arranged to place low temperature sodium coolant in an annular region between the hot coolant and the reactor vessel wall. A portion of the flow from the main coolant pumps is diverted into the cylindrical shell and cold sodium is pumped past the reactor vessel wall and thereby cooling it.
The present application relates to the application entitled "Plenum Separator System for Pool-Type Nuclear Reactors" by John E. Sharbaugh, Ser. No. 938,628, filed Aug. 31, 1978, and now abandoned.